Many modern video displays such as the Sony Grand Wega™ television use three microdisplays, one each for the primary colors of red, green, and blue. Each microdisplay can be, e.g., a liquid crystal display (LCD). To display a picture on the screen, the LCDs are illuminated by a bright lamp and through a set of lenses and prisms the final image is expanded to fill relatively large screens.
As understood herein, it is difficult at best to manufacture LCDs to have precisely uniform thicknesses, and even very small variations in thickness cause non-uniformity in the screen display such that some areas of the screen might appear to be brighter than others or tinged with artificial color. This undesirable appearance is magnified when the output of the LCD is optically expanded as is done in microdisplay televisions.
Accordingly, the present invention recognizes that a microdisplay uniformity adjustment process should be employed during TV production to compensate for imperfections in LCD thickness. For example, the uniformity adjustment process known as 3D gamma can be used. As understood herein, while the adjustment ideally is done on a pixel by pixel basis, to render the adjustment process feasible adjustment is performed on regions of pixels, e.g., the set of display pixels can be arranged in 372 regions and uniformity adjustment performed for each region. Essentially and with particular regard to 3D gamma adjustment, a calibration computer is operated to “adjust” the display controller chip by effectively “adding” or “subtracting” display element drive offsets (typically stored in the chip's memory) for each region as needed to achieve uniformity, usually with respect to a center region.
As further understood herein, dynamically variable irises have been provided at the input of the microdisplay LCDs to provide improved brightness and contrast expression especially in darker scenes. The present invention recognizes, however, that the introduction of dynamically variable irises requires multiple uniformity adjustments, i.e., one uniformity adjustment for each of a series of brightness levels. The present invention has critically observed that multiplying the number of uniformity adjustments that must be made during production can undesirably slow production significantly.
The invention still further understands that attempting to streamline uniformity adjustment using statistical analyses, e.g., by starting adjustment at some statistically average value, is less than optimum in the case of microdisplays, particularly for intermediate brightness levels. This is because the pattern formed for each set of adjustments is the combination of the overlap of three different microdisplays, each with its own unique pattern, which defies the use of conventional statistics. With these critical recognitions in mind, the invention herein is provided.